“So it is last night that we got a call to respond, that is toward this morning at four a.m., and at the moment, as Kenya Red Cross, we are on the ground tending to casualties, most of them with serious injuries,” said Muluka.

The Red Cross says five women and five children were among those killed in the attack.

Muluka says many homes were also burned during the raid.

"We’re talking about over 45 houses burnt, over 30 casualties, the situation is still tense and we have a group from Nairobi led by our secretary general that has just arrived at Tana Delta and casualties are being transported for more attention,” Muluka added.

This is the latest episode of violence between the Pokomo farming community and Orma herders, who have historically fought over resources.

But the violence has intensified this year. More than 110 people were killed in clashes between the two communities in September and October.

A Judicial Commission of Inquiry into the Tana River clashes has heard evidence that the violence is politically motivated, possibly due to redistricting in the area.

Defense Minister Yusuf Haji has been questioned by the commission following accusations that he had a hand in the violence, a charge he denies. And a member of parliament, Dhadho Ghodana, was arrested in September and charged with incitement.

As Kenya prepares for general elections in March, Red Cross officials are warning that inter-ethnic fighting this year has been worse than in the run-up to the last election in 2007. Violence that followed that disputed vote left more than 1,100 people dead and displaced hundreds of thousands more.